Optimization Of The Shape And Parameter For Hammer-driven Mole

With the development of deep space exploration, human become more and moreinterest to geological formation, evolution and physical and chemical properties ofsoil in space bodies. Unlike drilling, this paper focus on non-drilling technology forsitu detection, called mole. The mole is a device that can penetrate into the soilautomatically, which is compact, lightweight and low power consumption. In thispaper, we study the mole driven by hammer, concentrating on shape parametersoptimization of the front nose through theoretical analysis, simulation and penetrationtest to achieve a better penetration property.As the first part to contact with the soil, shape and parameter of the front nosemust have influence on penetration property. Based on soil mechanics, this paperproposed a convex and concave arc-shaped front nose, defined the configurationparameters and built the mechanical model between the two noses and soil. The modelnot only described failure of soil during penetration, and analyzed the stress state ofthe soil in failure regions in details.Mechanical model of the mole with the two noses were established during threepenetration stages to get the axial resistance formula respectively. Then, by means ofthe study of the physical and mechanical properties of lunar soil, we quantify therelevant parameters to study the influence of configuration parameters on the axialresistance, thus giving the comparative analysis of two noses to elect the optimumshape from the mechanical point of view.For the concave arc-shaped nose, dynamic model was established to get thepenetration depth for each impact. Then, by means of particle flow theory, stressanalysis of soil micro-soil and influence of the parameter on ratio of the horizontalspeed and vertical speed of micro-soil in slip line was given. Through linear weightingmethod, multi objective functions about penetration depth and velocity ratio wereturned into a single objective function to optimize the configuration parameter.Discrete element software EDEM was implied to simulate the lunar soil bymatching the parameters. Besides, penetration simulation of mole with the two noseswere realized to verify the theoretical analysis through analyze the simulation resultsof particle flow and axial resistance. Moreover, test bench was established andpenetration test was carried out for different noses to compare and elect the best noseand parameter.